Known systems of this type generally permit the release of the boot from the ski, or they permit only partial freedom of movement in the lateral or vertical direction, when falling forward or backward with respect to the ski, but without detachment from the latter. Exemplary in this respect are the systems described in German Pat. No. 2,907,365, German Utility Model 7 723 934, and German Pat. No. 3,310,739. In all of these disclosures, the partial or total release of the boot occurs between the holding elements, properly speaking, of the boot and an elastic locking device with which they cooperate.